The digitizing of analog information that is printed on paper or any other medium (hereinafter termed as ‘scanning’) while on-the-move is somewhat cumbersome due to the considerable size and weight of scanners available today. Mobile scanning solutions available today generally use linear image sensors which scan a document line by line. However, they typically require either motorized paper feeding (sheet-feed scanners) or a moving carriage (flatbed scanners) which results in significant weight and bulk. An additional limitation of sheet-feed scanners is their inability to directly scan bounded materials such as passports, magazine pages or multi-paged documents.
Instead of utilizing linear image sensors, an alternative method of mobile scanning involves taking a digital photograph with digital image capturing devices such as digital cameras. These digital image capturing devices typically comprise an area image sensor. Area image sensors can capture the entire scan area on its sensing surface rather than capturing the image line-by-line as with linear sensors. Without the need for paper feeding, such digital image capturing devices have the ability to scan bounded and multi-paged materials. Also, such image capturing devices are usually lighter and smaller than conventional scanners because they do not require any motor or moving mechanism (gear, belt, pulley, carriage, plate, etc). Although this can result in a relatively more portable scanning solution, disadvantages include image distortion due to ambient light. For example, a bright spot from an overhead light source can be seen on the captured image. Shadows can also appear when there is blockage of light, for instance, when a user's hand is positioned above the target object when taking a digital photo.
Furthermore, images may be blurred if the user's hand is not steady and/or the flash is not used. If a flash is used, a flash spot usually appears on the digital image, especially if the document to be scanned is of the glossy/specular reflectable type. The conventional way to solve this is by moving the light source far away or/and to the bottom side of the photo sensor. In this way, the flash spot will appear outside of the document scan area. However, a lot of light power is wasted and the light output is very low. Furthermore, the size of the scanner cannot be made small if the photo sensor and light source were to be in the same housing.
In addition, if the image is not aimed directly to the paper plane, there can be a perspective distortion.
A need therefore exists to provide, a method of scanning and an apparatus thereof that seeks to address at least one of the abovementioned problems.